A gear reducer of this type is known from the European patent application EP-A1-1 793 143 filed by the present applicant.
One of the main defects of the gear reducer described in this document is constituted by the fact that it is difficult to disassemble. In fact, for example, in the case in which it is necessary to change a worn disc of the torque limiter, the worm gear assembly must first be disassembled from the worm to allow extraction of the whole worm gear assembly.